"Davide is on the list, but to bring to the grid next year a driver with no experience is a huge step for them," said Boullier. "I've done it twice with them: first with [Vitaly] Petrov and then with a semi-rookie [Romain] Grosjean, and I think I've had enough, to be honest with you. Davide is on the list because we consider him as a good driver, as a GP2 champion, but it's true that if you favor a scenario for next year, it will be a driver with experience.

"If we cannot find any driver with experience fitting the strategy of the team, obviously we will go for a rookie driver and then Davide is obviously on the top of the list. It looks harsh, I'm sorry, but it's true."

Meanwhile, regarding Grosjean's prospects of staying on with Lotus in 2014, he said, "Romain has a contract signed anyway for next year. It's just, say, a matter of confirmation. We are being prudent. But I think it's on its way to be confirmed soon.

"We are definitely pleased with his performance -- since Germany, actually. Clearly, something switched on, and he is working better. I mean, the same tire story as well, the latest spec of tires suit a little bit more his driving style than Kimi [Räikkönen]'s one. But yes, we are pleased that he is stepping up. We don't have a policy of driver No. 1 and No. 2, but we needed him obviously to step up, yes."